Hi @Pency
It is possible to display tickets bought online on the app too, and print out tickets bought via the SBB Mobile app at SBB.ch. The only precondition for this is that the tickets are purchased via the same user account.
Already purchased tickets can't be added into the wallet afterwards. It is only possible to do so directly after the purchase when you are asked if you want to add it.
Greetings, ValerieS